Presidential candidates Hillary Clinton and Donald Trump will meet Monday night at Hofstra University in Hempstead, New York, for the first of their three scheduled debates. The event begins at 9 p.m. ET and will be shown on all major networks and the cable news stations, with most channels starting their coverage at least an hour beforehand. (You can watch it live online right here.)

Election Day is only six weeks away, with national and state polls showing a tight race that could still go either way. Experts say that this debate could be the last essential moment of the 2016 campaign, the final opportunity for either candidate to change voters' minds and swing them one way or the other. Viewership could reach Super Bowl–like levels, possibly even surpassing 100 million people watching, which would make it by far the most-viewed debate of all time.

Hosted by moderator Lester Holt of NBC, the 90-minute-long debate will be split into six 15-minute segments and cover three major topics: the economy, national security and America's direction. According the Commission on Presidential Debates, which has organized and administrated the presidential debates since 1988, here is what to expect:

The moderator will open each segment with a question, after which each candidate will have two minutes to respond. Candidates will then have an opportunity to respond to each other. The moderator will use the balance of the time in the segment for a deeper discussion of the topic.

The two candidates have gone about preparing for the debate in drastically different ways. The Republican nominee, Trump, has eschewed the standard preparation methods of mock-debating and intensive study of the issues, preferring instead to rely on his instincts and stick with the image of being not-your-usual-politician that has gotten him this far. Clinton, the Democrat, has been reading up on policy papers and psychological analyses of Trump, practicing arguments against a Trump stand-in -- often for 90 minutes at a time, starting at 9 p.m., just as the actual debate will.

The next debate will be held on October 9 at Washington University in St. Louis, Missouri. The third takes place October 19 at the University of Nevada in Las Vegas.